Pillar formwork

ABSTRACT

A column formwork for use in concrete construction is described, comprising a planar member 1 constituting the formwork, and at least one connecting section provided for form-fit connecting two opposing edges  3, 3 ′ of the planar member ( 1 ) and thus for constituting a tube segment, wherein at least the connecting-section surface facing the planar member 1 exhibits a substantially constant curvature that substantially corresponds to the curvature of the tube segment.

FIELD OF THE INVENTION

The present invention is directed to a column formwork for use in concrete construction.

BACKGROUND OF THE INVENTION

Column formworks are used in concrete construction to build columns, supports, or similar concrete elements. Recently, in addition to conventional steel and wood formworks, wound formworks of sheet metal, cardboard, or synthetic material have increasingly been employed. In the case of wound cardboard formworks, the outer formwork tube, which primarily serves to hold the formwork together, is constructed of paperboard or cardboard. After the column has been concreted and the concrete has set, the outer formwork element is removed by tearing it open by means of an integrated tear strip.

A column formwork comprising a multilayered wound flat material is known from DE 295 18 077. The flat material is a polyethylene-coated paper sheet. Due to the multilayered winding, paper layers and polyethylene layers alternate in the wall of the formwork tube in this column formwork.

DE 296 09 259 discloses a column formwork comprising a tube segment divided along its longitudinal axis. Connecting means are provided in the area of the dividing line to hold the formwork together. To construct this column formwork, a tube segment is slit open once along its longitudinal axis. To ensure simple removal, it is recommended that the column formwork be constructed of a synthetic material that can be bent apart when removing the formwork. To the inside of the column formwork is applied an auxiliary formwork material, which avoids form marks resulting from the dividing line.

These known column formworks have various disadvantages in common. For one thing, the formworks exhibit an extremely large volume, thus causing problems, particularly during transportation, that are reflected in high costs. The column formwork interior, provided for filling up with concrete, is nothing other than dead volume during transportation, and thus only a very small quantity can be transported in each load. The column formwork according to DE 296 09 259 also exhibits this problem, as it involves shape-retentive synthetic material tubing that can be bent apart briefly with sufficient expenditure of force only during removal.

Moreover, the above-described column formworks are single-use products, as the outer formwork element is removed from the cured concrete by tearing it open. Reuse of the column formwork is thus excluded. In the case of the column formwork according to DE 296 09 259, this problem is solved only partially. Although the outer part of the formwork can be reused, the necessary interior lining having e.g. a tube of thin paperboard is a single-use product.

DISCLOSURE OF THE INVENTION

This is where the present invention begins. It is intended to provide a column formwork that can be reused and easily transported. According to the present invention, this object is solved by the column formwork according to independent claim 1. Other advantageous aspects, details, and embodiments of the present invention are evident from the dependent claims, the description, and the drawings.

The present invention is based on the idea of using, not, as previously typical, prefabricated tubes as column formworks in concrete construction, but rather planar members equipped with connecting sections, through which a form-fit connection of two opposing edges of the planar member is possible. The material comprising the planar member must satisfy two conflicting conditions: on one hand, it must exhibit sufficient strength to withstand the pressure of the poured concrete, and on the other hand, it must exhibit sufficient elasticity to be able to be bent into a tube with no difficulty. In particular, this tube must remain dimensionally stable, that is, circular in diameter, under the pressure of concrete, that is, after the concrete is poured.

The column formwork according to the present invention for use in concrete construction comprises a planar member constituting the formwork, and at least one connecting section, provided for form-fit connecting two opposing edges of the planar member and thus for forming a tube segment, wherein at least the connecting-section surface facing the planar member exhibits a substantially constant curvature that substantially corresponds to the curvature of the tube segment. In this way, it is achieved that the column formwork takes on a round shape. If connecting sections having no curvature are used, the bent planar member would take on a slightly tear-shaped form and thus cause unsatisfactory results in the concrete parts. Slight differences between the curvature of the connecting section and the curvature of the tube segment are tolerated within the context of the present invention, since acceptable results can be obtained nonetheless.

The column formwork according to the present invention can be transported with no difficulty in large quantities in a flat state before bending it into a tube.

The use of the term “substantially constant curvature” is intended to make clear that manufacturing-dependent deviations from a constant curvature are, of course, tolerated, as long as they are not so marked that the column formwork exhibits a diameter that deviates substantially from a circular diameter.

According to a preferred embodiment of the present invention, the planar member comprises an elastic synthetic material. Such a material fulfills the two above-mentioned conditions especially well, namely sufficient shape-retentiveness after the concrete is poured and, at the same time, sufficient elasticity that allows bending into a tube with no difficulty. Such a column formwork exhibits the great advantage that no single-use materials are provided, such as the typically used cardboard, thus facilitating multiple reusage of the formwork.

The two opposing edges of the planar member must be form-fit connected together. To do this, at least two connecting sections are generally used. Advantageously, each of these connecting sections is attached to the planar member flush with one edge of the planar member. However, in the context of the present invention, the connecting sections can, in principle, also be attached to the planar member at a short or even a somewhat long distance from the edges to be connected. In such a case, the tongues described below for connecting the connecting sections must be adjusted accordingly in their dimensions or e.g. replaced by flexible bands.

However, an embodiment having just one connecting section attached near an edge of the planar member and protruding over this edge is also conceivable. The part of the connecting section protruding out over the edge is then connected with the planar member near the opposing edge after the planar member is bent into a tube segment. This connection can, in principle, take place in any manner, for example through glueing. However, the planar member can also exhibit e.g. projections that engage in corresponding recesses of the connecting section and thus facilitate a secure form-fit connection of the opposing edges.

Although the two above-mentioned conditions “stability of dimension” and “elasticity” are naturally fulfilled to a sufficient extent by a number of materials that can, in principle, be used in any thickness, certain materials used in certain thicknesses yield particularly good results for the purpose of very easy handling. For these reasons, both the use of fiber reinforced materials, of fiber reinforced synthetic materials, or of polyester, especially synthetic fiber reinforced materials, glass fiber reinforced materials, and carbon reinforced materials, especially glass fiber reinforced materials or carbon reinforced synthetic materials, especially fiber reinforced polyester, as the elastic synthetic material, and a planar member having a thickness of 0.5 to 5 mm, especially having a thickness of 1 to 4 mm, particularly preferably having a thickness of 1.2 to 3 mm, are preferred embodiments of the present invention. Planar members having a thickness of 1.4 to 2.5 mm are particularly well suited, and those having a thickness of 1.5 to 2 mm are most particularly preferred.

For reasons of reduced variety of form of the connecting sections, the connecting-section surface facing away from the planar member can additionally be provided with a substantially constant curvature, this curvature then differing from the curvature of the tube segment. In this way, a connecting section can be used for column formworks of varying diameters.

Although the column formworks according to the present invention can be used for concreting columns of greatly varying diameters, and in principle even for concreting columns of any diameter, column formworks having a typical concrete construction diameter of 100 to 2000 mm, especially of 200 to 1000 mm, are preferred. Diameters of 200 to 450 mm, of 250 to 500 mm, of 500 to 900 mm, and of 600 to 1000 mm are particularly preferred.

The connecting sections can be affixed to the planar member in various ways, namely e.g. through glueing, riveting, nailing, or welding. Glueing the connecting section and the planar member is particularly preferred because doing so causes no visible traces in the finished concrete parts.

Column formworks having connecting sections that exhibit, in the direction of the tube-segment tangent perpendicular to the tube-segment axis, an extension of 1 to 50%, especially 3 to 25% of the tube-segment diameter, are particularly preferred embodiments of the present invention. This ensures that, after the concrete is poured into the formwork, the connecting sections do not detach from the planar member. Pouring the concrete creates strong forces perpendicular to the formwork wall, and there is thus a risk of the formwork breaking apart along the planar member edge held together by the connecting sections. To prevent such breaking apart, the connecting sections must be appropriately tightly connected together, and an appropriately strong connection between connecting section and planar member must be ensured. For this reason, connecting sections that exhibit, in the direction of the tube-segment tangent perpendicular to the tube-segment axis, an extension of 5 to 15%, especially of about 10% of the tube-segment diameter, are most particularly preferred.

In view of the above-mentioned column diameters typical in concrete construction, connecting sections that exhibit, in the direction of the tube-segment tangent perpendicular to the tube-segment axis, an extension of 10 to 100 mm, especially from 20 to 75 mm, are preferred. Connecting sections that exhibit, in the direction of the tube-segment tangent perpendicular to the longitudinal axis of the tube segment, an extension of 30 to 50 mm, especially of 35 to 45 mm, are particularly preferred.

In principle, the connecting sections can be constructed of any kind of sufficiently dimensionally stable material. The connecting sections are preferably constructed of synthetic material, and the connecting sections are particularly preferably constructed of polyester, of a fiber reinforced synthetic material, especially of glass fiber reinforced synthetic material or carbon reinforced synthetic material, particularly preferably of glass fiber reinforced polyester or carbon reinforced polyester.

Most particularly advantageous characteristics result when the connecting sections and the planar member comprise the same material. In this way, an especially simple and tight connection between the parts is possible through glueing.

To ensure a secure, form-fit connection of the opposing edges of the planar member, in the context of the present invention, it is particularly preferred that the connecting sections extend in the direction of the tube segment axis over the entire length of the tube segment. In this way, the edges of the planar member can be form-fit connected over the entire length of the column formwork with particularly great strength and precision.

The connecting sections can, in principle, be mechanically connected with one another in any manner known in formwork engineering, thus for example using clamps, wedges, locks, or bolts. In the context of the present invention, connecting sections that exhibit grooves and tongues are preferred. To connect the edges of the planar member, one tongue of one connecting section engages in a groove of the other connecting section with a precise fit. The stable cohesion of the edges of the planar member is ensured e.g. through a bolt that is guided through bores in the connecting sections and then screwed down.

Another important condition for achieving good results in the form of an excellent surface finish of the concrete columns is preventing water and cement paste from penetrating the formwork. At the junction of the edges of the planar member, there is a risk that, in the case of an insufficiently form-fit junction, water penetration and thus bleeding of fine concrete components could occur at the seam. This can cause visible unevenness on the surface of the concrete column. For this reason, a planar member and connecting sections are preferably used whose edges are especially smooth due to an appropriate subsequent treatment such as grinding or polishing, and that facilitate a very good, precisely fitting connection. Furthermore, according to a particularly preferred embodiment of the present invention, the tongues of the connecting sections are equipped with seals, thus preventing penetration of water through the connecting sections.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is intended to be explained in greater detail below by reference to an exemplary embodiment in association with the drawings, wherein

FIG. 1 shows a cutaway of a cross-section through a column formwork according to the present invention;

FIG. 2 shows a part of a cross-section through a column formwork according to the present invention, having a larger diameter compared with the column formwork of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a cutaway of a cross-section through a column formwork. The planar member 1 is equipped with the connecting sections 2 and 2′, which are each attached adjacent to the edges 3, 3′ of the planar member. The connecting-section surface 4, 4′ facing the planar member 1 exhibits a constant curvature, the curvature substantially corresponding to the curvature of the tube segment. In this way, it is achieved that the column formwork takes on a precisely round shape. The connecting-section surface 5, 5′ facing away from the planar member likewise exhibits a constant curvature, the surface 5, 5′ of the connecting section shown being more sharply curved than the surface 4, 4′. The edges 3, 3′ of the planar member 1 exhibit a highly precise fit. The connecting section 5 is equipped with two tongues 6, while the connecting section 5′ exhibits two corresponding grooves. However, each of the two connecting sections can also be equipped with one tongue and one groove. The connection between the two connecting sections and thus the positive connection of the two edges of the planar member results through an engagement of the tongues 6 in the corresponding grooves. The penetration of water through the connecting sections 2, 2′ is prevented by the longitudinally running seals 7. The required securing of the connection through a clamp that covers the two connecting sections 2, 2′, or a bolt that is guided through the two connecting sections 2, 2′ and then screwed down, is not shown.

FIG. 2 likewise shows a cutaway of a cross-section through a column formwork. In FIG. 2, the extension t of connecting section 2 in the direction of the tube-segment tangent perpendicular to the axis of the tube segment is emphasized.

List of Reference Numbers

1 Planar member

2, 2′ Connecting section

3, 3′ Edges of the planar member

4, 4′ Connecting section surface facing the planar member

5, 5′ Connecting section surface facing away from the planar member

6 Tongues

t Extension of a connecting section in the direction of the tube-segment tangent perpendicular to the tube segment axis 

1-17. (canceled)
 18. A column formwork for use in concrete construction, comprising a planar formation (1) constituting the formwork, and at least one connecting section provided for positively connecting two opposing edges (3, 3′) of the planar formation (1) and thus for constituting a tube segment, wherein at least the connecting-section surface (4, 4′) facing the planar formation (1) exhibits a substantially constant curvature and the curvature substantially corresponds to the curvature of the tube segment, and wherein the planar formation (1) exhibits a thickness of 1 to 4 mm and comprises an elastic synthetic material, namely a fiber reinforced synthetic material or a carbon reinforced synthetic material.
 19. The column formwork according to claim 18, characterized in that a glass fiber reinforced synthetic material or glass fiber reinforced or carbon reinforced polyester is used as the elastic synthetic material.
 20. The column formwork according to claim 18, characterized in that the planar formation (1) exhibits a thickness of 1.2 to 3 mm.
 21. The column formwork according to claim 18, characterized in that the planar formation (1) exhibits a thickness of 1.4 to 2.5 mm, especially a thickness of 1.5 to 2 mm.
 22. The column formwork according to claim 18, characterized in that, additionally, the connecting-section (2, 2′) surface (5, 5′) facing away from planar formation (1) exhibits a constant curvature, this curvature differing from the curvature of the tube segment.
 23. The column formwork according to claim 18, characterized in that the connecting section (2, 2′) is constructed of synthetic material.
 24. The column formwork according to claim 18, characterized in that the connecting section (2, 2′) is constructed of polyester, of a fiber reinforced synthetic material, especially of glass fiber reinforced or carbon reinforced synthetic material, particularly preferably of glass fiber reinforced or carbon reinforced polyester.
 25. The column formwork according to claim 18, characterized in that the planar formation (1) and the connecting section (2, 2′) consist of the same material.
 26. The column formwork according to claim 18, characterized in that the connecting section (2, 2′) extends in the direction of the tube-segment axis over the entire length of the tube segment.
 27. A column formwork for use in concrete construction, comprising a planar formation (1) constituting the formwork, and two connecting sections (2, 2′) provided for positively connecting two opposing edges (3, 3′) of the planar formation (1) and thus for constituting a tube segment, wherein at least the connecting-section surface (4, 4′) facing the planar formation (1) exhibits a substantially constant curvature and the curvature substantially corresponds to the curvature of the tube segment, and wherein the planar formation (1) exhibits a thickness of 1 to 4 mm and comprises an elastic synthetic material, namely a fiber reinforced synthetic material or a carbon reinforced synthetic material.
 28. The column formwork according to claim 27, characterized in that a glass fiber reinforced synthetic material or glass fiber reinforced or carbon reinforced polyester is used as the elastic synthetic material.
 29. The column formwork according to claim 27, characterized in that the planar formation (1) exhibits a thickness of 1.2 to 3 mm.
 30. The column formwork according to claim 27, characterized in that the planar formation (1) exhibits a thickness of 1.4 to 2.5 mm, especially a thickness of 1.5 to 2 mm.
 31. The column formwork according to claim 27, characterized in that, additionally, the connecting-sections (2, 2′) surface (5, 5′) facing away from planar formation (1) exhibits a constant curvature, this curvature differing from the curvature of the tube segment.
 32. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) exhibit, in the direction of the tube-segment tangent perpendicular to the tube-segment axis, an extension (t) of 1 to 50%, especially 3 to 25% of the tube-segment diameter.
 33. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) exhibit, in the direction of the tube-segment tangent perpendicular to the tube-segment axis, an extension (t) of 5 to 15%, especially about 10% of the tube-segment diameter.
 34. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) exhibit, in the direction of the tube-segment tangent perpendicular to the tube-segment axis, an extension (t) of 10 to 100 mm, especially 20 to 75 mm.
 35. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) exhibit, in the direction of the tube-segment tangent perpendicular to the longitudinal axis of the tube segment, an extension (t) of 30 to 50 mm, especially 35 to 45 mm.
 36. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) are constructed of synthetic material.
 37. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) are constructed of polyester, of a fiber reinforced synthetic material, especially of glass fiber reinforced or carbon reinforced synthetic material, particularly preferably of glass fiber reinforced or carbon reinforced polyester.
 38. The column formwork according to claim 27, characterized in that the planar formation (1) and the connecting sections (2, 2′) consist of the same material.
 39. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) extend in the direction of the tube-segment axis over the entire length of the tube segment.
 40. The column formwork according to claim 27, characterized in that the connecting sections (2, 2′) exhibit grooves and tongues (6) that engage precisely to connect the edges (3, 3′) of the planar formation (1).
 41. The column formwork according to claim 27, characterized in that the grooves (6) exhibit longitudinally running seals (7). 